A measurement of cosmic ray deuterium from 0.5–2.9 GeV/nucleon

The rare isotopes ^(2)H and ^(3)He in cosmic rays are believed to originate mainly from the interaction of high energy protons and helium with the galactic interstellar medium. The unique propagation history of these rare isotopes provides important constraints on galactic cosmic ray source spectra and on models for their propagation within the Galaxy. Hydrogen and helium isotopes were measured with the balloon-borne experiment, IMAX, which flew from Lynn Lake, Manitoba in 1992. The energy spectrum of deuterium between 0.5 and 3.2 GeV/nucleon measured by the IMAX experiment as well as previously published results of ^(3)He from the same instrument will be compared with predictions of cosmic ray galactic propagation models. The observed composition of the light isotopes is found to be generally consistent with the predictions of the standard Leaky Box Model derived to fit observations of heavier nucle

Cosmic Ray Antiproton Observations by the Isotope Matter-Antimatter Experiment; 0.2 to 3.2 GeV

We have positively identified sixteen mass-resolved cosmic ray anti.protons with energies between 0.2 and 3.2 GeV using the IMAX balloon-borne magnetic spectrometer. Mass was determined by velocity vs. magnetic rigidity techniques using a high resolution time-of-flight system and silica-aerogel Cherenkov detectors. The anti.protons are clearly separated from the low-mass particle background. Here the measurement technique, data analysis, and resulting proton and antiproton mass histograms are presented

The Cosmic Ray ^3He/^4He Ratio from 200 MeV per Nucleon^(-1) to 3.7 GeV per Nucleon^(-1)

The abundances of cosmic-ray helium isotopes between 0.2 and 3.7 GeV nucleon^(-1) were measured by the Isotope Matter Antimatter Experiment (IMAX) during a flight from Lynn Lake, Manitoba, Canada on 1992 July 16-17. The IMAX balloon-borne magnetic spectrometer realized a direct measurement of the charge, the velocity, and the rigidity of cosmic rays using plastic scintillators, a high-resolution time-of-flight system, and two silica-aerogel Cerenkov counters in conjunction with a drift chamber/multiwire proportional chamber tracking system. About 75,000 helium isotopes are identified by their mass using the velocity versus magnetic rigidity technique. The measured ^3He/^4He ratios are corrected to the top of the atmosphere, and a comparison with previous data is given. The observed isotopic composition is found to be generally consistent with the predictions of a standard leaky box model of cosmic-ray transport in the Galaxy

Measurement of 0.25-3.2 GeV antiprotons in the cosmic radiation

The balloon-borne Isotope Matter-Antimatter Experiment (IMAX) was flown from Lynn Lake, Manitoba, Canada on 16–17 July 1992. Using velocity and magnetic rigidity to determine mass, we have directly measured the abundances of cosmic ray antiprotons and protons in the energy range from 0.25 to 3.2 GeV. Both the absolute flux of antiprotons and the antiproton/proton ratio are consistent with recent theoretical work in which antiprotons are produced as secondary products of cosmic ray interactions with the interstellar medium. This consistency implies a lower limit to the antiproton lifetime of ∼10 to the 7th yr

Measurement of the Absolute Proton and Helium Flux at the Top of the Atmosphere using IMAX

The balloon-borne experiment "IMAX" launched from Lynn Lake, Canada in 1992 has been used to measure the cosmic ray proton and helium spectra from 0.2 GeV/n to about 200 GeV/n. The IMAX apparatus was designed to search for antiprotons and light isotopes using a superconducting magnet spectrometer with ancillary scintillators, time-of-flight, and aerogel cherenkov detectors. Using redundant detectors an extensive examination of the instrument efficiency was carried out. We present here the absolute spectra of protons and helium corrected to the top of the atmosphere

Correlation of Source Abundances of Ultraheavy Cosmic Rays with First Ionization Potential - Results from HEAO-3

The cosmic-ray-source abundances inferred from HEAO-3 observation by the Heavy Nuclei Experiment for 30 < Z < 60 generally follow the correlation with first-ionization potential which has previously been observed for Z < 30. However the low Ge abundance suggests that the elemental "volatility" may be an organizing factor

ISOMAX: A Balloon-borne Instrument to Study Beryllium and Other Light Isotopes in the Cosmic Radiation

The Isotope Magnet Experiment (ISOMAX), a balloon-borne magnetic rigidity spectrometer designed to measure the light isotopes of the cosmic radiation, is currently under construction. A major goal of the experiment is accurate measurement of the abundance of the radioactive isotope ^(10)Be up to relativistic energies (~ 4 GeV/nucleon). ISOMAX will make use of state-of-the-art instrument technology based on evolutionary development of detectors previously constructed by this collaboration. The ISOMAX detector complement will include high-resolution drift chambers for trajectory detennination, a time-of-flight system, and a Cherenkov detector utilizing silica aerogel radiators. For rare isotopes, a large exposure factor is required to obtain statistlcaJly significant results. ISOMAX is specifically designed to take advantage of the emerging capability for long-duration balloon flights, with a two week dewar lifetime and low-power electronics. The first flight of ISOMAX is planned for 1995

Cosmic Ray Antiproton Observations from 0.2 to 3.2 GeV

The Isotope Matter Antimatter Experiment (IMAX) has detected 16 antiprotons, in the energy range from 0.2 to 3.2 GeV. This result provides significant improvement in statistical accuracy over previous cosmic ray antiproton measurements in the same energy range. This measurement has been corrected for instrumental and atmospheric losses, yielding top-of-the-atmosphere antiproton to proton ratios in three energy intervals. These results are consistent with recent theoretical predictions in which antiprotons are produced as secondary cosmic rays and are transported through the galaxy according to the standard Leaky Box model